1. Field of the Invention
The invention relates to a thermoplastic composition having improved properties such as impact strength. It particularly relates to blends of a copolymer of styrene and maleic anhydride and elastomeric EPM or EPDM which has been modified with specified functional groups.
2. Description of Information Disclosures
Various blends of engineering thermoplastics and elastomers are known.
U.S. Pat. No. 4,742,116 discloses a thermoplastic moulding composition comprising a mixture of (A) copolymer of styrene and/or alpha methylstyrene and maleic anhydride, and (B) an ethylene-propylene modified rubber or an ethylene-propylene-diene modified rubber, said rubber having been modified by grafting thereto a compound containing hydroxyl, amide or amine groups.
European Publication 0140422-A1 published May 8, 1985 (European Patent Application 842013807 filed Sep. 27, 1984) discloses a process for preparing a thermoplastic moulding composition by mixing styrene and/or methylstyrene, maleic anhydride with a rubber modified with hydroxyl groups (e.g. EPM or EPDM rubber), in the presence of a specified amount of reaction accelerator such as an organic compound of a metal of groups II, III, and IV of the Periodic Table of Elements.
U.S. Pat. No. 3,856,765 discloses copolymers of ethylene, propylene, with or without a diene, and functional monomer which may be a 2-substituted-5-norbornene.
European Patent Publication 0321293 published Jun. 21, 1989 (European Patent Application 88311965-3 filed Dec. 16, 1988) discloses improved polybutylene terephthalate molding composition comprising a minor amount of a copolymer of ethylene, a higher alpha olefin, optionally a polymerizable non-conjugated diene, and a 2-substituted-5-norbornene in which the substituent of said norbornene may be carboxyl, hydroxyalkyl, amino, N-aminoalkyl or N-aminoaryl.
European Publication No. 0295076 published Dec. 14, 1988 based on European patent application 88305222.7 filed June 8, 1988 discloses ethylene-propylene elastomers comprising a 2-substituted-5-norbornene monomer.
U.S. Pat. 4,251,644 discloses blends of modified EPM or modified EPDM polymers with polyesters such as dacron or polyamides such as nylon. The modified EPM or EPDM incorporates highly polar groups such as amine groups, amide groups, thio groups, ether groups, and ester groups.
Although the known blends of thermoplastic engineering plastic and elastomers have some improved properties, there is still a need to improve the properties of thermoplastic engineering plastics, such as, for example, the copolymers of styrene and maleic anhydride.
It has now been found that properties, such as impact strength of a thermoplastic, such as a copolymer of styrene and maleic anhydride, can be improved by blending it with an elastomeric EP or EPDM which has been modified to comprise specified functional groups.